Christopher Huw Hill

Large Dynamic Range High Frequency Fully Differential CMOS Transconductance Amplifier

A large dynamic range high frequency fully differential CMOS transconductance amplifier is introduced. It is based on the linear transconductance element proposed in [8] combined with the common-mode feedback circuit in [9]. The original transconductance and common-mode circuits which use two supply voltages are modified for operation under a single power supply. The performance of the complete transconductance amplifier is analysed in details. Simulation results of the whole circuit are also presented, which show that with a single 5 V supply, bandwidth in excess of 300 MHz, THD below 0.7% for a 1 Vpk–pk differential input signal, and dynamic range in excess of 70 dB can be achieved for the fully differential transconductance amplifier.

Bisindolylmaleimide inhibitors of protein kinase C. Further conformational restriction of a tertiary amine side chain.

Abstract A pharmacophore model for the localisation of the cationic binding site of bisindolylmaleimide PKC inhibitors is described. This model has been used to guide selection of further conformationally restricted tertiary amine analogues, culminating in the identification and synthesis of the potent and highly selective PKC inhibitor, Ro 32-0557.

Low-power fully differential CMOS filter for video frequencies

The authors describe a new low-power fully differential second-order continuous-time low-pass filter for use at video frequencies. The filter uses a single active device in combination with MOSFET resistors and grounded capacitors to achieve very low-power consumption and large dynamic range. The ideal integrator is realized using an internally compensated op-amp consisting of only current mirrors and voltage buffers, while the lossy integrator is implemented by a single passive RC circuit. The filter has been simulated using a CMOS process. Results show that with a single 5-V power supply, cutoff frequency can be tuned from 3.5 to 8 MHz, dynamic range is better than 67 dB and power consumption is less than 1.7 mW.

Structure-based design of peptidomimetic antagonists of p56lck SH2 Domain

Starting from the tetrapeptide Ac-pYEEI-NHMe and using a structure-based approach, we have designed and synthesised a peptidomimetic ligand for p56(lck) SH2 domain containing a conformationally restricted replacement for the two glutamate residues. We have explored replacments for the isoleucine residue in the pY+3 pocket and thus identified 1-(R)-amino-3-(S)-indaneacetic acid as the most potent replacement. We also report the X-ray crystal structures of two of the antagonists.

Single-amplifier integrator-based low power CMOS filter for video frequency applications

This paper describes a new low power fully differential second-order continuous-time low pass filter for use at video frequencies. The filter uses a single active device in combination with MOSFET resistors and grounded capacitors to achieve very low power consumption, small chip area and large dynamic range. The ideal integrator is realised using an internally compensated opamp consisting of only current mirrors and voltage buffers, whilst the lossy integrator is implemented by a single passive RC circuit. The filter has been simulated using a CMOS process. Results show that with a single 5 V power supply, cut-off frequency can be tuned from 3.5 MHz to 8 MHz, dynamic range is better than 67 dB, and power consumption is less than 1.7 mW.

Low noise, low distortion, high frequency, fully differential CMOS transconductor

This paper describes a CMOS transconductance element based upon two differential pairs whose outputs are summed to give a linear transfer characteristic. The circuit has been simulated using a 2 /spl mu/m process from MOSIS, and results show that with a single 5 V supply, bandwidth in excess of 300 MHz, THD below 0.7% for a 1 V/sub pk-pk/ differential input signal, and dynamic range in excess of 70 dB can be achieved.