This paper presents a new low-voltage pseudo-differential continuous-time CMOS transconductor for wideband
applications. The proposed cell is based on a feedforward cancellation of the input common-mode signal and keeps the
input common mode voltage constant, while the transconductance is easily tunable through a continuous bias voltage.
Linearity is preserved during the tuning process for a moderate range of transconductance values. Simulation results for a
0.35 &mgr;m CMOS design show a 1:2 G<sub>m</sub> tuning range with an almost constant bandwidth over 600 MHz. Total harmonic
distortion figures are below -60 dB over the whole range at 10 MHz up to a 200 &mgr;A<sub>p-p</sub> differential output. The proposed
cell consumes less than 1.2 mW from a single 2.0 V supply.
In this paper we present a low-voltage preamplifier destined for optical-fiber communication front-ends in the standard Gigabit Ethernet. Designed in a low-cost 0.35 μm CMOS technology, the circuit can work with a single 1.8 V supply voltage, consumes only 6.2 mW and exhibits a tunable transimpedance from 50 to 65 dBΩ with bit rates up to 1.5 Gb/s.
A novel high performance envelope detector structure is proposed in this work. This circuit does not
need the traditional compensation between keeping and tracking required in these circuits due to a system
by what the signal peaks are held in two periods and combined to obtain the envelope of the signal. At the
same time, it solves some drawbacks due to switches used in these kinds of circuits when this technique
has been employed, such as nonlinearities due to charge injection in switches, which reduces the linearity
of these circuits. Thus, it is shown the superior performance of this circuit obtaining for a signal at
10MHz small ripple (<1%), very fast settling (0.4&mgr;s) and using smaller capacitive area (-60%) than
conventional peak detectors. Furthermore, this envelope detector has a dynamic range above 40dB for
nonlinearities below 1dB.