A track&hold-AGC suitable for downconversion by subsampling

To date, high-speed CMOS transistors can operate in the GHz frequency range and as result high sampling frequency can be obtained. Thus, a receiver architecture using the sub-sampling principle to downconvert the signal can be now considered as a promising alternative to other kinds of architectures. In effect, sub-sampling systems are potentially more compact and more efficient, because the A/D converter is closer the antenna. In this paper, we show how it is possible to use switched-capacitor techniques to make a track-and-hold mixer and an AGC in the same circuit. This circuit is destined for the front-end of a receiver. For the basic configuration of the circuit, measurements have shown that a signal around 900 MHz could be demodulated to low frequency. An IIP3 of 19 dBm has been proved and at the same time, unfortunately, a noise figure of 20 dBm has been obtained.