U.S. Philips Corporation

Motorola Corporation

Knud Holtvoeth

Andreas H Wichern

Wilfried E Knop

Edgar Herbert Callaway, Jr

James G Mittel

Burkhard Dick

Vance H Peterson

A receiver has a crystal oscillator (10) whose frequency can be adjusted in response to temperature compensation (TC) and automatic frequency control (afc) signals. The TC and afc signals are summed and applied to an op-amp (70) having a fixed gain functioning as a current to voltage converter. An output of the op-amp (70) is applied to the crystal oscillator (10). If the receiver is switched--on and--off in accordance with say a time division protocol, the output of the op-amp (70) is applied by way of a switch (72) to a storage circuit (30,C) which when the switch is open applies a bias voltage on the crystal oscillator (10) to maintain its output frequency.

Radio receivers

A receiver including an rf amplifier(14) having an input, an output and a gain control input(38), for deriving a gain control signal. A gain control (36) responsive to the gain control signal. The gain control (36) comprises at least 2 parallel arranged bias currents (40,42,44), at least one(42 or 44) of the 2 bias current means including switching means(SW1 or SW2) responsive to a control voltage varying by a predetermined amount relative to a reference voltage(V.sub.ref1 or V.sub.ref2) for actuating the switching means(SW1 or SW2) to connect or disconnect the bias current (42 or 44) to or from the gain control input.

A receiver (100) for receiving an input signal and generating an output signal therefrom has a switchable gain circuit (104) with a stepwise variable gain control (118), a local oscillator (106) and an automatic gain control (AGC) detector (114) with a response for detecting a level of the output signal and generating an AGC signal indicative of the level of the output signal and a state machine (116) being responsive to the AGC signal generating a control signal at the stepwise variable gain control to increase or decrease a gain of the switchable gain circuit in discrete stepwise steps.

Selective call receivers with stepwise variable gain control

A high frequency amplifier circuit arrangement has an output current path having one end coupled to a reference potential for supplying an alternating signal current at an output terminal. The influence of parasitic inductances in the output current path on the amplitude of the alternating signal current is reduced or cancelled in that compensation is provided for the influence of a parasitic inductance in the coupling between the output current path and the reference potential by means of a compensation circuit which applies an alternating compensation current to a (first) node between the output current path and the parasitic inductance. This compensation current is in phase opposition to and of at least substantially the same magnitude as the alternating signal current.

Growing community of inventors

Hamburg, Germany

Knud Holtvoeth