Abstract: Transmission of a high frequency signal is provided by a passive mixer. The passive mixer receives a low frequency signal as an input. The passive mixer includes a plurality of transistors each with a gate, a source, and a drain. The passive mixer also includes a local oscillator connected to the gates of the transistors. The gates of the transistors are also connected to a DC bias proportional to the threshold voltage of the transistors. In addition, an output of the passive mixer may be attenuated by a passive attenuator wherein both the passive attenuator and passive mixer are substantially free of quiescent current.

Abstract: A method of transferring data between a first electrical component (16) and a second electrical component (18), which are both coupled to a common oscillator (62) that oscillates at a first frequency, the first electrical component (16) generating a first bit stream having a second frequency that is a fraction of the first frequency and having a first number of bits, generating an indicator signal having a third frequency that is a fraction of the first frequency and that is indicative of a type of data represented by the first bit stream, and coupling the first bit stream and the indicator signal to the second electrical component. The second electrical component (18) sampling the first bit stream and the indicator signal at a fourth frequency that is substantially identical to the second frequency, thereby recovering the first bit stream generated by the first electrical component (16) and determining the type of data contained in the first bit stream.

Abstract: An integrated image reject mixer (150) generates precise quadrature components using highly matched local-oscillator (LO) path and intermediate frequency (IF) path resistor-capacitor (RC) phase shifting networks (131, 138). Because the LO signal from a local oscillator (127) has a constant amplitude, a phase detector (136) feedback loop easily maintains an accurate ninety-degree phase difference between the quadrature LO signals (122, 124) from the LO path phase shifting network (131). Because the two phase shifting networks are matched, the feedback control signal (137) from the phase detector (136) can also be used to maintain an accurate ninety-degree phase difference between the quadrature IF signals (123, 128) from the IF path phase shifting network (138) despite the dynamically-varying amplitude of the IF signal. Thus, this image reject mixer uses only components that may be easily integrated into an integrated circuit.

Abstract: A radio (100) has a combined phase locked loop (PLL) (207) and an automatic frequency control (AFC) loop (215, 109, 111) and a method of operating the same. A mixer (201) converts the received RF signal (117) to an intermediate frequency (IF) signal (219) responsive to an injection signal (217). The PLL (207) locks the injection signal (217) to the received RF signal (117) responsive to a difference between the IF signal (219) and a reference signal (119). The AFC loop (215, 109, 111) locks the reference signal (119) to the received RF signal (117) responsive to a difference between the injection signal (217) and the reference signal (119).

Abstract: A filter assembly (100) includes a ceramic block filter (102) and shielding bracket (132) which surface mounts to a printed circuit board (152) for interconnecting to radio frequency devices, such as a radio transceiver. The bracket (132) is soldered to the filter (102) and includes two openings (136 and 137) for exposing input/output electrodes (106 and 107) of the filter. The printed circuit board (152) includes an opening (162) shaped to accept the filter (102) and bracket (132) when inserted therein. Transmission lines (156 and 157) are disposed on tabs (158 and 159) and are reflow soldered to the corresponding electrodes (106 and 107) of the filter. The bracket (132) includes two tabs (134) which are reflow soldered to grounded portions of the circuitry on the top side of the printed circuit board (152).