Measured CMOS Switched High-Quality Capacitors in a Reconfigurable Matching Network

Abstract

Switched capacitors are here investigated for use in reconfigurable matching networks, particularly for digital video broadcasting-handheld (DVB-H) frequencies. A 0.13-μm CMOS circuit is evaluated through both simulations and measurements. Source grounded nMOS transistors are used to switch high-quality metal capacitors located above metal layer 8. The quality factor and tuning range depend on frequency, switch voltage, capacitor size, and transistor width. There is a clear tradeoff between quality factor and tuning range, and measurements show quality factors above 50, 100, and 150 at tuning ranges of 3.9, 2.4, and 1.6, respectively. A reconfigurable matching network with the switched capacitors has been realized using external inductors and the measured matching domain for the DVB-H frequency band is shown. The total loss of the network is 1.0 dB, a result of the high-quality switched capacitors.