A current-mode 1 kHz/10 kHz low-voltage integrated analogue PLL for lock-in portable applications

We present a low-supply voltage (2 V) low-power consumption (500 muW) analogue phase-locked loop (PLL), working at two low frequencies (1 and 10 kHz), to be used in an integrated lock-in amplifier. An externally settable control bit allows the switching operation between the two different frequencies. The circuit has been designed in a standard 0.6-mum CMOS technology and differs from the standard analogue PLL architectures for the current mode implementation of both the loop filter and of the oscillator. Three different locked waveforms (sinusoidal, triangular, squared) can be obtained at the PLL output. Simulation results, obtained through the use of PSPICE and using accurate transistor models, will be proposed. The pull-in ranges are about +/-250 Hz around 1 and +/-1.3 kHz around 10 kHz, with pull-in times of about 10 and 4 ms, respectively. Copyright (C) 2003 John Wiley Sons, Ltd.