Abstract: A radiotelephone handset (400) is adapted to accommodate a plurality of distinctive telephone appearances. The radiotelephone handset (400) includes a housing (402) having a front housing portion (414) and a rear housing portion (416) and a faceplate (104) attached to the front housing portion and having an outer surface (434) having a distinctive user interface appearance and an inner surface (436). The radiotelephone handset (400) further includes a keypad cover (418) movable between a first position and a second position.

Abstract: A dual mode communication device (102) includes a first radio (124) operable according to a first mode and a second radio (126) operable according to a second mode. A common user interface (130) controls both the first radio and the second radio. Using two, complete, preexisting radios reduces development and manufacturing costs of the dual mode communication device.

Abstract: Performance of a radiotelephone (104) in a CDMA communication system (100) is enhanced using a receiver searcher (114) that includes a matched filter (128) to capture the pilot energies of all receivable transmissions from a base station (102) and other nearby base stations. A detected PN sequence is compared with a predetermined PN sequence stored at the radiotelephone (104). The predetermined PN sequence includes, for example, the last 512 chips in the short PN sequence used for spreading the in-phase channel and the quadrature-phase channel.

Abstract: A comparator circuit (100) produces a binary output voltage at an output (109) in response to a time varying input signal received at an input (108). The comparator circuit includes an output circuit (106) having a first current mirror (202), a second current mirror (204), a bias circuit (206) and a helping current source (208). Bias currents are applied in response to the state of the output voltage at the output to increase the gain and the hysteresis of the output circuit.

Abstract: A communication device (100) includes a plurality of receiver fingers (112, 114, 116) for receiving a spread spectrum communication signal. Each receiver finger includes a received signal strength indication (RSSI) circuit (400). The RSSI circuit (400) includes an energy calculator (406) and a filter (410, 412) for producing a filtered signal which indicates signal quality. A first comparator (414) produces a primary lock indication when the filtered signal exceeds a primary lock threshold. A second comparator (418) produces a secondary lock indication when the filtered signal exceeds a secondary lock threshold. The bandwidth of the RSSI circuit (400) can be varied between a first bandwidth for providing the primary lock indication for traffic channel decoder and a second bandwidth for providing the secondary lock indication for the power control bit decoder. This allows performance to be tailored to the individual requirements of the traffic channel decoding and the power control channel decoding.

Abstract: A mobile station (104) in a DS-CDMA communication system (100) has receiver diversity. A first antenna (130) receives signals over a communications channel (101) from a base station (102). A second antenna (132) receives signals which are delayed in a delay element (142) by one or more chip times and combined in a summer (148) with signals from the first antenna. The combined signals are presented to a RAKE receiver (112) for decoding and demodulation. When discernible multipath energy is present to the point where much of the received signal energy is not accounted for in the assigned RAKE receiver fingers, the second antenna is switched out to avoid increasing the level of interference.

Abstract: Prior to entry into a low-power sleep mode, a radiotelephone (104) in a radiotelephone system (100) calculates in advance the timing required to wake up selected portions of the radiotelephone and stores the calculated wakeup times in registers (216). Also prior to entry into sleep mode, local timing of the radiotelephone is synchronized to received PN roll boundaries from the radiotelephone system. In the sleep mode, the radiotelephone uses a sleep timer (210) to simulate system timing. When the sleep timer (210) matches the stored wakeup times, the radiotelephone re-activates the selected portions of the radiotelephone, such as an oscillator (116) and a radio frequency portion (109) of an analog front end (108), to exit the sleep mode and reacquire communication with the system. This also permits an early exit from sleep mode, for example to service an interrupt, while maintaining system timing.

Abstract: A method and apparatus provides an indication of active handsets in a cordless telephone system (100). A user enters an inquiry (204) using either a handset (104) or the user interface (120) of the base station (102). The base station (102) pings or queries (210) each registered handset (106, 108, 110, 112) to establish a list of active handsets. The list of active handsets is then transmitted (228) to the handset (104) from which the inquiry was received or is displayed using the user interface (120) of the base station (102). This permits the user to learn what other users are actively registered with the base station (102) for call forwarding, intercom operation or for use of any other user convenience features of the cordless telephone system (100).

Abstract: A method and apparatus provides control of the gain of an input amplifier (306) in a radio receiver (300), such as in a radiotelephone handset (104). The radio receiver (300) includes an automatic gain control circuit (318). The automatic gain control circuit (318) includes a timer circuit (370) which provides asynchronous, digital automatic gain control circuit to perform a coarse gain adjustment. The automatic gain control circuit (318) further includes an integrator (366) which provides analog automatic gain control for providing remaining needed gain regulation. The automatic gain control circuit (318) provides substantial reduction in input signal acquisition time for the radio receiver (300).

Abstract: An operational amplifier includes a differential amplifier including a first transistor (120) and a second transistor (122), a gain stage (125), a first folded cascode stage (104) and a second folded cascode stage 106, and a first telescopic stage (108) and a second telescopic stage (110). The folded cascode stages respond to current in the differential amplifier to control the output signal, and the telescopic stages respond to a differential voltage produced by the gain stage to control the output signal.

Abstract: A method and apparatus control blanking of a display (106) in a communication device (100) such as a battery powered radiotelephone. The communication device (100) includes a clock operated blanking timer 317. When the blanking timer 317 elapses, the communication device (100) blanks the display (106) a predetermined time after a key press of a keypad (108). A switch (310) detects when the communication device (100) is in use. In response to this detection, the communication device (100) maintains supply of operating power to the display (106), overriding the blanking timer 317. When a user is holding the communication device (100) adjacent to the user's head, an earpiece sensor (312) provides an indication of this condition. In response to the indication, the display (106) is immediately blanked to conserve operating power in the battery (124).

Abstract: A dual-modulus prescaler (100) has improved performance for high-speed operation. A timing signal is developed from a flip flop circuit (106) two and one-half clock cycles before the last stage of the prescaler is clocked. The timing signal is used to produce a selector signal to gate a multiplexer (112). Because of the early generation of the timing signal, the multiplexer selection process is removed from the critical path. The remaining delay through the multiplexer is minimal to minimize the critical path of the prescaler.