Architecture for low-voltage switched-current complex bandpassfilters

An architecture for the switched-current (SI) realisation of complex filters is presented, based upon the signal flow-graph method. Also briefly discussed is a practical design flow for SI complex filters, based on that for traditional real SI filter designs. A verification of the architecture is given via the design and simulation of a fifth-order complex SI bandpass filter with 1 MHz centre frequency and bandwidth, implemented using a low-voltage class AB neutralised SI scheme     

Low-voltage class AB switched-current technique

A low-voltage class AB technique for high-speed and medium-resolution switched-current (SI) signal processing is described. The technique essentially uses the basic class AB SI memory with error-neutralisation and dummy switch schemes to reduce output conductance and charge-injection errors. Simulated results of the balanced class AB memory and bilinear integrator operating at 100 MHz sampling frequency and 1.6 V supply indicates that precision better than 8 bits is entirely feasible over the extreme process and temperature corners     

Current amplitude control circuits suitable for current-modeoscillators

A novel current amplitude control circuit suitable for current-mode oscillators is proposed. The circuit is a modified version of the well-known Gilbert gain cell. The technique obtains independent control of oscillation amplitude and small-signal current gain. As an example, the amplitude control circuit is applied to a current-mode oscillator. Simulations were carried out using HSPICE with 0.8 μm Nortel BiCMOS technology and Motorola RF transistors. Simulated results demonstrate that the nonlinear current gain control circuit behaves in a well defined manner. Low distortion and high frequency oscillations are easily obtained when the circuit is applied to a current-mode oscillator