摘要:
The RF section of a communication device (100) includes a receiver (106), a transmitter (108), first injection frequency generation circuit (120), and an intermediate frequency (IF) generation circuit (124). The IF generation circuit has a shared output coupled to both the receiver and transmitter, as well as a control circuit (118) for feedback control purposes. The IF generation circuit is used to generate IF for both the receiver and transmitter, thus using fewer components that two separate IF generation circuits. It includes two differently tuned voltage controlled oscillators (202, 204) which are selectively and exclusively powered by first and second power switches (234, 236), respectively. The control circuit provides a single control voltage corresponding to a desired frequency pair to both VCOs at a common control input, then selects the appropriate VCO depending on whether the communication device is receiving or transmitting.
摘要:
A transmitter has a loop switch (132) and a feedback switch (127), which are operated by a control circuit (134). An unamplified value is obtained by connecting a cartesian demodulator (126) with the input to a power amplifier (118), applying a fixed baseband signal level to the input of the cartesian modulator, and measuring the output level of the cartesian demodulator. An amplified value is obtained by connecting the output of the power amplifier to the cartesian demodulator, again applying a fixed baseband signal level, and measuring the output of the demodulator. The amplified and unamplified values are compared by the control circuit, and the power amplifier gain is adjusted by varying the gain adjust signal (138), if necessary.
摘要:
An active circuit includes an amplifying transistor (102), a voltage reference (208), and an active bias circuit. The active bias circuit controls the operating point of the amplifying transistor, and includes a bias transistor (224) which is controlled by the voltage reference and the collector current of the amplifying transistor. As the temperature of the amplifying transistor changes, the tendency of the collector current to change is counter-acted by the bias transistor and the voltage reference.
摘要:
A low loss electronic radio frequency (RF) switch (100) for switching RF energy between an antenna port (115), a receiver port (113) and a transmit port (101) used in a two-way radio transceiver. The RF switch includes a first diode (105) connected between the transmit port (101) and the antenna port (115). A first capacitor (103) is connected between the transmit port (101) and a ground potential while an inductor (107) and second capacitor (111) are serially connected between the antenna port (115) and a receive port (113). A second diode (109) is connected between the inductor (107) and the second capacitor (111) and the ground potential. The antenna port (115) is normally connected with the receive port (113) when idle. When direct current is applied to the transmit port (101) the first diode (105) and second diode (109) are biased into a low impedance state connecting the antenna port (115) to the transmit port (101) and isolating the receive port (113) from the antenna port (115).
摘要:
First and second shielding portions (110, 112) formed of electroless plated plastic enclose a radio frequency (RF) board (108). Bosses (148) extend from inner surfaces (130, 142) of the first and second shielding portions (110, 112) to make contact with compressible ground clip members (126) located on the RF board (108).
摘要:
Battery (300) includes a first redundant limiting circuit (302) for limiting the voltage and current levels which are outputted by the first limited battery output (308). A second redundant limiting circuit (304) provides for a second limited battery output (310). Connected to both the first (308) and second (310) battery outputs is a fault monitoring circuit (306), which monitors for any faults such as electrical shorts, occurring at any of the two battery outputs (308 or 310). The fault monitoring circuit (306) interrupts the appropriate output, if a fault, or a current limiting condition occurs. Battery (300) allows for radios which would otherwise not be able to achieve intrinsic safe level approvals to attain such approvals.
摘要:
A radio-frequency amplifier (50) has an impedance transformation network (66) with a control input (70) for controlling the transformation characteristic of the transformation network (66). The radio-frequency amplifier (50) amplifies an input signal to produce an amplified radio-frequency output signal to a load (68). The control circuit selects a power level for the output signal, in response to a control signal, by transforming the impedance of the load to a transformed impedance at the output of the radio-frequency amplifier, so that the efficiency of the radio-frequency amplifier is not substantially degraded as the power level for the output signal is changed.
摘要:
A phase lock loop (100) includes a dual-state charge pump (120) having a first current source (220), a second current source (230) coupled in series to the first current source, a third current source (240), a fourth current source (250) coupled in series to the third current source, and control circuitry (210) coupled to the first, second, third, and fourth current sources. The charge pump can be programmed to be in an adapt mode with large up and down currents or in a normal mode with small up and down currents. The duration of the adapt mode can be programmed by a timer. The phase lock loop has a wide loop bandwidth and a faster lock time during the adapt mode and a narrow loop bandwidth and less phase noise during the normal mode.
摘要:
An antenna coupler (100) for use in a mobile adaptor (102, 300) transfers radio frequency (RF) energy between a portable radio antenna system (204) and an external antenna (124) with minimal coupling losses. The antenna coupler (100) includes a resonator patch (110) and an electromagnetic tuning element (112) forming side walls on a substrate for receiving the portable antenna system (204). The electromagnetic tuning element (112) controls the impedance between the resonator patch (110) and the portable antenna system (204) while the resonator patch transfers the RF energy between the portable radio antenna and the external antenna (124).
摘要:
An RF interconnect assembly includes a ground plane (124) and a radio circuit (109), and an RF connector (126) having a signal conductor (127) and a ground conductor (130) where the ground conductor (130) is coupled to the ground plane (124). Located a predetermined distance (d) above the ground plane (124), a spring contact (140) provides a constant impedance transmission line connection between the RF connector (126) and the radio circuit (109).