Abstract: Digital amplifying circuitry delays a digital data signal (INR) to produce an output signal (VoutR). The delayed digital data signal is converted to an analog signal (VinR) for amplifying by an amplifier (10R). Signal amplitude information (S_R[n]) contained in the incoming digital data signal is detected during the delaying. The signal amplitude information is converted to a first control signal (S_Io_NEG[n]) in response to which an adjustable maximum available supply current of the amplifier is produced of least sufficient magnitude to avoid distortion during the amplifying to produce the output signal. The signal amplitude information also is converted to a second control signal (S_AMPLITUDE[n]) in response to which a supply voltage (VNEG) of the amplifier is controlled.

Abstract: Digital amplifying circuitry delays a digital data signal (INR) to produce an output signal (VoutR). The delayed digital data signal is converted to an analog signal (VinR) for amplifying by an amplifier (10R). Signal amplitude information (S_R[n]) contained in the incoming digital data signal is detected during the delaying. The signal amplitude information is converted to a first control signal (S_Io_NEG[n]) in response to which an adjustable maximum available supply current of the amplifier is produced of least sufficient magnitude to avoid distortion during the amplifying to produce the output signal. The signal amplitude information also is converted to a second control signal (S_AMPLITUDE[n]) in response to which a supply voltage (VNEG) of the amplifier is controlled.

Abstract: Dual band voltage controlled oscillators (VCOs) incorporate a combiner circuit with a single output operable at two widely separated frequency bands such as 900 MHz and 1.8 GHz, for example. The combiner circuit includes a duplexer used as a combiner on the outputs of the VCOs. The duplexer can be realized in transmission line or inductor configurations. The use of the duplexer improves spurious performance and phase noise by more than 10 dB between the two operating frequency bands and supplies band rejection at the non-operating frequency.

Abstract: A method (100) for mechanically tuning a VCO that has a resonant stripline having vias in predetermined locations connected through a circuit board to ground. This includes a step (104) of measuring the operating frequency of the VCO. A following step (106) includes calculating an amount of frequency shift needed to achieve a desired frequency. A following step (108) matches the amount of frequency shift needed to values in a look-up table of frequency shifts versus via locations to determine which vias locations will provide the proper amount of frequency shift. A last step (110) includes mechanically disconnecting from ground the via locations indicated in the third step such that the desired frequency is achieved. This method (100) of tuning allows VCO frequency adjustment after final assembly avoiding problems of frequency shifts that can occur due to the placement of a metal lid on the circuit board after assembly.

Abstract: A voltage controlled oscillator (10) operable on two widely separated frequency bands of 800 MHz and 1.9 GHz, for example. The two operable frequency modes are controlled by changing base bias voltages on at least two transistors with commonly connected emitters. A base circuit of each transistor is connected to an independent resonator and tuning element and shares a common feedback reactance. By increasing a base bias voltage of first transistor relative the a second transistor, an associated first base circuit is turned on and allowed to oscillate at a first frequency while a second base circuit is turned off preventing oscillation at a second frequency. Correspondingly, by decreasing the base bias voltage the first base circuit is turned off and the second base circuit is turned on. The transistors share a common collector connection and output providing either one of the two frequencies.