X [1,2]. The presented Bluetooth Low-Energy (BLE) transceiver, as shown in Fig. 13.3.1, was purposely designed with a classic double-frequency VCO architecture to avoid these inherent weaknesses, but still significantly reduces the power consumption of designs of the same architecture [3,4]. In order to ease application, an on-chip DC-DC converter supports battery operation between 0.9V and 3.3V. An on-chip T/R switch, RX balun and impedance matching allow 50Ω chip antennae to be used directly on the single-ended RFIO pin, without the need for external RF filtering. This enables minimum-sized modules and a fast time-to-market.25:T4f4,This paper describes the design of an accurate and static complementary constant- $g_{{m}}$ biasing circuit for Nauta's transconductors in low-power low-frequency CMOS $g_{m}\mathchar"707B C$ bandpass filters and their optimization and trimming for process and temperature independent filter performance. Experimental results are presented for a prototype third-order Butterworth bandpass filter in a 180-nm CMOS process with a 2-MHz bandwidth and center frequency. These filters are appropriate for the channel selection stage of a Zigbee receiver and show with a single trim for process over a 120 $^{\circ}$ C temperature range less than 2% deviation in the bandwidth and center frequency. Mismatch and process corner variation are demonstrated to have only a minimal effect on this performance.

Johan Haanstra

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