A telemetry receiver for an implantable medical device such as a cardiac pacemaker has an RF antenna coupled to a telemetry circuit that includes an out-of-band rejection filter comprising a microelectromechanical filter. The telemetry circuit further includes an amplifier coupled to the microelectromechanical filter and a demodulator coupled to the amplifier. The filter, amplifier and demodulator are all fabricated on a common integrated circuit die. A multichannel telemetry receiver for an implantable medical device has a plurality of microelectromechanical bandpass filters defining individual channels. A multiplexing circuit selects the signal of an individual bandpass filter channel for application to a demodulator circuit that recovers programming data from a modulated RF transmission from a programming unit. Identification of a preferred data transmission channel for communication of programming data to the implanted medical device is determined by obtaining samples of the signals being passed by each of a plurality of microelectromechanical bandpass filters that define individual channels and evaluating the samples to determine the noise level for each channel. The implantable medical device may be programmed to receive downlink telemetry communications from a programming unit on the channel identified as being the preferred data transmission channel having the lowest noise level.