Novel two-o.a. three-resistor variable phase inverting amplifier

A new active phase-compensated inverting amplifier is proposed. The amplifier circuit employs two o.a.s and three resistors and has an infinite input impedance. The proposed amplifier is also suitable for phase correction in two-integrator loop filters.     

High-Input and Low-Output Impedance Voltage-Mode Universal Biquadratic Filter Using DDCCs

A new three inputs and single output voltage-mode universal biquadratic filter with high-input and low-output impedance using three plus-type differential difference current conveyors, two grounded capacitors and two grounded resistors is presented. The proposed circuit offers the following features: realization of all the standard filter functions, that is, high-pass, bandpass, low-pass, notch, and all-pass filters, no requirements for component matching conditions, the use of only grounded capacitors and resistors, high-input and low-output impedance and low active and passive sensitivities.     

Insensitive current-mode universal filter with minimum componentsusing dual-output current conveyors

A novel universal current-mode active filter with four inputs and one output is presented, which contains only three dual-output current conveyors. Two grounded capacitors and two grounded resistors. The circuit is very advantageous from an integration point of view. The proposed active filter realises all filter responses without any matching conditions at high impedance output and has low passive and active sensitivities     

High output impedance current-mode universal biquadratic filters with five inputs using multi-output CCIIs

Three current-mode universal biquadratic filters each with five input terminals and one output terminal are presented. The first proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and three resistors. This circuit offers the following advantageous features: orthogonal controllability of resonance angular frequency and quality factor, high output impedance, the versatility to synthesize all standard filter types without component matching condition and using grounded capacitors. The second proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and two resistors. This circuit offers the following advantageous features: using minimum passive components, high output impedance, the versatility to synthesize all standard filter types without component matching condition and using grounded capacitors. The third proposed circuit uses three multi-output second-generation current conveyors, two grounded capacitors and three grounded resistors. This circuit offers the following advantageous features: the versatility to synthesize all standard filter types, high output impedance and using only grounded passive components. Each of the proposed circuits can get five kinds of filter functions by using only one current input signal.     

Anti-blocker design techniques for MOSFET-C filters for directconversion receivers

A linearized MOSFET-C low-pass filter suitable for a baseband channel selection filter for a direct conversion receiver is presented. Using polysilicon resistors instead of MOSFET resistors in the input and output part, the filter achieves very high out-of-band linearity but maintains the original transfer function under the control of a continuous on-chip cutoff tuning scheme. In order to enhance the linearity of the triode-mode MOSFET variable resistors, the gates of the MOSFETs are driven by a charge pump in the cutoff control loop. Also, an appropriate gain scaling is implemented to lower the input referred noise, thus making the out-of-band dynamic range wider. This fifth-order elliptic filter achieves -2 dBV in-band IIP3, +28 dBV out-of-band IIP3, +94 dBV out-of-band IIP2 and -87 dBV input-referred noise, and dissipates 6.2 mW from a 2.7-V supply; the on-chip continuous automatic tuning system dissipates 4.1 mW     

High Input Impedance Voltage-Mode Universal Biquadratic Filter with Three Inputs Using DDCCs

A new high input impedance voltage-mode universal biquadratic filter with three input terminals and five output terminals is presented. The proposed circuit uses three plus-type differential difference current conveyors, two grounded resistors and two grounded capacitors. The proposed circuit can realize all the standard filter functions: lowpass, bandpass, highpass, notch and allpass, without component matching conditions. The proposed circuit offers the features of high input impedance, low active and passive sensitivities and the use of only grounded resistors and capacitors.     

Voltage/Current-Mode Universal Filter Using FTFN and CFA

A novel configuration for realizing voltage/current-mode (VM/CM) universal filter using a single four terminal floating nullor (FTFN), a single current feedback amplifier (CFA), two capacitors and three resistors is presented. The VM configuration has three inputs and a single output and implements all the five generic filtering functions through the selection of inputs. This topology enjoys cascadability and does not require any additional active element for facilitating the filter realizations. The same circuit in current-mode has a single input and four outputs and realizes LP, HP and two BP responses simultaneously from which AP and Notch can also be realized. This topology uses grounded resistors and capacitors which are ideal for monolithic integration. Both the topologies enjoy orthogonal control of natural frequency (ω₀) and quality factor (Q) by the grounded resistors. The topologies enjoy low active and passive sensitivity figures. Experimental and PSPICE simulation results are also included.     

Novel versatile insensitive universal current-mode biquad employing two second-generation current conveyors

A new universal current-mode biquad with two inputs and three outputs or three inputs and two outputs using only two second-generation current conveyors and four grounded/virtual-grounded passive elements is proposed. The proposed circuit has the following advantages: simultaneous realization of five generic current-mode filter signals from the same configuration; no requirements of any cancellation constraints; employment of two grounded capacitors ideal for integrated circuit implementation; employment of two grounded/virtually grounded resistors suitable for voltage control; orthogonal adjustment of ω₀/Q and ω₀ through two separate grounded/virtually-grounded resistors; high output impedance good for cascadability for the current-mode circuits; and low active and passive sensitivities.     

High Input Impedance Voltage-Mode Universal Biquadratic Filter with One Input and Five Outputs Using Current Conveyors

A new high input impedance voltage-mode universal biquadratic filter with one input terminal and five output terminals is presented. The proposed circuit uses three differential voltage current conveyors (DVCCs), four resistors, and two grounded capacitors. The proposed circuit can realize all the standard filter functions—lowpass, bandpass, highpass, notch, and allpass—simultaneously, without changing the passive elements. The proposed circuit enjoys the features of high input impedance, orthogonal control of resonance angular frequency and quality factor, use of only grounded capacitors, and low active and passive sensitivities.     

Enhanced phase noise modeling of fractional-N frequency synthesizers

Mathematical models for the behavior of fractional-N phase-locked-loop frequency synthesizers (Frac-N) are presented. The models are intended for calculating rms phase error and determining spurs in the output of Frac-N. The models describe noise contributions due to the charge pump (CP), the phase frequency detector (PFD), the loop filter, the voltage control oscillator, and the delta-sigma modulator. Models are presented for the effects of static CP gain mismatch, CP dynamic mismatch and PFD reset delay mismatch. A simple analytic expression shows the level of /spl Delta//spl Sigma/ sequence noise caused by static CP current mismatch. We further show that un-equal rise time and fall time constants of the CP result in dynamic mismatch noise. Reset delay mismatch in PFD is shown to also contribute significantly to close-in phase noise. The model takes into account the reduction in CP thermal and flicker noise due to the changing duty cycle of Frac-N CP. Our model is therefore useful in characterizing the noise performance of Frac-N at the system-level, simplifying the design of fractional-N synthesizers and transmitters. Analytical and simulated results are compared and show good agreement with prior published data on Frac-N realizations.     

Analog CMOS building blocks for custom and semicustom applications

Standard analog building blocks developed for use in custom and semicustom LSI and VLSI designs are described. The analog blocks are built using a digital CMOS process modified to include high-value resistors and voltage independent capacitors. Designs for operational amplifiers, programmable voltage sources, comparators, bandgap voltage references, unit resistors, capacitors, and n-p-n devices are discussed. Performance characteristics including unity-gain bandwidth, output drive, output impedance, and common mode range are reviewed. MOS noise data, subthreshold operation, and device matching are analyzed. Layout guidelines are proposed as well as applications and limitations of the analog building blocks.     

Realization of Current-Mode Third Order Butterworth Filters Employing Equal Valued Passive Elements and Unity Gain Buffers

This paper describes current-mode third-order Butterworth filter topologies realized with unity gain active elements and minimum number of passive components. All capacitors and resistors are equal valued. The core of the circuit realizes HP, BP and LP functions easily. The filter exhibits high output impedance. Experimental results are included to verify theory.     

Analog CMOS Building Blocks for Custom and Semicustom Applications

Standard analog building blocks developed for use in custom and semicustom LSI and VLSI designs are described. The analog blocks are built using a digital CMOS process modified to include high-value resistors and voltage independent capacitors. Designs for operational amplifiers, programmable voltage sources, comparators, band gap voltage references, unit resistors, capacitors, and n-p-n devices are discussed. Performance characteristics including unity-gain bandwidth, output drive, output impedance, and common mode range are reviewed. MOS noise data subthreshold operation, and device matching are analyzed. Layout guidelines are proposed as well as applications and limitations of the analog building blocks.     

New Universal Filter with One Input and Five Outputs Using Current-Feedback Amplifiers

A new universal voltage-mode second-order filter circuit is presented. The circuit uses five current-feedback operational amplifiers, two grounded capacitors three grounded resistors and three floating resistors. The circuit can realize all the standard filter functions; lowpass, highpass, bandpass, notch and allpass, without changing the passive elements. The proposed circuit enjoys independent grounded-resistance-control of the natural frequency and the bandwidth, low output impedances, high input impedance as well as low active and passive sensitivities.     

一种自动频率调谐高频跨导电容滤波器

采用BiCMOS工艺,设计了可自动频率调谐的高频跨导-电容滤波器.在跨导电路中,使用有源负阻稳定共模信号,提高直流增益.在频率调谐电路中,利用锁相回路比较参考频率与滤波器输出频率的相差,进而调节滤波器特性.     

有源环路滤波器的设计分析

在PLL频率合成器中,环路滤波器的设计对PLL的输出性能有着非常重要的影响。然而在某些场合VCO要求的调谐电压比PLL的充电泵输出电压高得多,这种情况下就必须选用有源环路滤波器。有源环路滤波器基本上可以分为差分结构和单端结构2种,可根据实际应用的PLL充电泵输出来进行选择。在进行有源环路滤波器的设计过程中,选择合理的环路滤波器拓扑结构以及低噪声放大器将最小化对PLL相位噪声的影响。     

A novel COA-based electronically adjustable current-mode instrumentation amplifier topology

In this paper a new topology for implementing Current-Mode Instrumentation Amplifiers (CMIA) is presented. The proposed CMIA is based on two single input-multiple output (SI-MO) current operational amplifiers (COAs) as basic building blocks and 2 resistors. To electronically control the differential-mode gain, a transistor operating in triode region is used which acts as a variable resistor. The significant feature of the proposed CMIA is that the active building blocks operate in closed loop configuration. Therefore it exhibits numerous remarkable features such as improved frequency performance, low THD and very low input impedance. In addition, it has fully differential output which reduces the output noise and increases its application. The proposed CMIA is analyzed and simulated with SPICE program using parameters of 0.18 µm CMOS technology and supply voltage of ±0.9 V.     

Current-mode electronically tunable biquadratic filters consisting of only CCCIIs and grounded capacitors

In this paper, a current-mode (CM) analog filter for simultaneously realizing high output impedance low-pass, band-pass and high-pass analog responses besides high output impedance notch and all-pass analog filter responses with interconnection of the relevant output currents, is presented. Also, two CM filters for simultaneously providing high output impedance universal filter responses are derived from the proposed one. All of the introduced CM topologies employ a canonical number of only grounded capacitors without requiring any resistors, and do not need critical component matching conditions. All of the developed circuits have low input impedance and high output impedance resulting in easy cascadability with other CM ones. Frequency dependent non-ideal gain and parasitic impedance effects on the performance of the presented first filter are investigated as examples. In order the show the performance of the filter and verify the theory, simulations are accomplished with SPICE program.     

A 1.75-GHz highly integrated narrow-band CMOS transmitter withharmonic-rejection mixers

A highly integrated 1.75-GHz 0.35-μm CMOS transmitter is described. The I/Q modulator-based transmitter facilitates integration through the use of a unique mixer, termed a harmonic-rejection mixer, and a wide loop bandwidth phase-locked loop (PLL) for the RF synthesizer. The harmonic-rejection mixers are used to eliminate the need for a discrete IF filter and the use of a wide loop bandwidth PLL allowed for the complete integration of the synthesizers using low-Q components while achieving low phase noise. The entire transmit signal path from the digital-to-analog converters to the power amplifier, including two fully integrated frequency synthesizers, is integrated into a single-chip solution. The transmitter was tested with a testing buffer before the power amplifier (PA) and achieved less than 1.3° rms phase error when modulating a DCS-1800 GMSK signal. The prototype consumed 151 mA from a 3-V supply. A class-C PA, capable of driving 25 dBm off-chip, was included and the output was compared to the testing buffer with little change in the transmitter performance     

High input impedance voltage-mode lowpass, bandpass and highpassfilter using current-feedback amplifiers

A new configuration for realising high input impedance lowpass, bandpass and highpass filters simultaneously by using three current-feedback amplifiers, three grounded capacitors, three grounded resistors and one floating resistor is presented. The proposed circuit offers the following features: realisation of lowpass, bandpass and highpass signals from the same configuration, no requirements for component matching conditions, orthogonal control of ω₀ and Q, the use of grounded capacitors, low active and passive sensitivities and low output impedance