An automatic gain control (AGC) transimpedance amplifier (TIA) uses a differential structure with feedback PIN diodes to adjust the loop gain of the amplifier automatically to maintain stability over a wide dynamic range when converting optical power using a photodiode to an electrical signal. A stable DC current derived from the photodiode current sets the voltage gain of the amplifier. The use of ultra-linear long carrier lifetime PIN diodes assures the transimpedance feedback resistance is linear. The AGC function adjusts the gain of the TIA to provide a linear stable differential transresistance controlled by the photodiode current; a linear stable AGC function using current supplied by the photodiode; an improvement of about 10 db of the transresistance dynamic range; and reduces the need for internal and external circuitry needed to provide the same function. The TIA is applicable to CATV optical systems which have very strict linearity requirements.

A half duplex amplifier for a cable network.

A network interface device includes an active path between an entry port and a first input/output port. The network interface device also includes a passive path between the entry port and a second input/output port. The network interface device also includes a buffer in the active path configured to absorb, attenuate, terminate, or isolate radio-frequency (RF) signals. The network interface device also includes a switching element in the active path configured to selectively bypass the buffer during normal operating conditions.

An example communication system includes a frequency-segmented power amplifier (PA) circuit that includes a plurality of PA segments. Each PA segment is configured to amplify a portion of a PA input signal in a different frequency band to generate a respective output signal (PA segment output signal). The frequency-segmented PA circuit further includes a combiner, configured to combine PA segment output signals from different PA segments to provide a power-amplified version of the PA input signal. Implementing such a frequency-segmented PA circuit may result in significant improvement in PA efficiency.

Described examples provide for digital communication circuits and systems that implement digital pre-distortion (DPD). In an example, a circuit includes a baseband DPD circuit, up-conversion circuitry, and feedback circuitry. The baseband DPD circuit comprises a baseband signal path and pre-distortion path. The pre-distortion path is configured to generate a pre-distortion signal based on the baseband signal. The baseband DPD circuit includes a first adder configured to add the baseband signal from the baseband signal path and the pre-distortion signal from the pre-distortion path to generate a pre-distorted baseband signal. The up-conversion circuitry is configured to convert the pre-distorted baseband signal to a radio frequency signal. The up-conversion circuitry is configured to be coupled to an input of a cable television (CATV) amplifier. The feedback circuitry comprises a DPD engine configured to determine a configuration of the pre-distortion path based on an output signal on the output of the CATV amplifier.

A method of bidirectional amplification of proprietary TDMA (Time-Division Multiple Access) data modulated signals over CATV infrastructure is described. A method of upstream/downstream switching based on carrier detection/measurement originated from the master and slave modems embodiment is described, along with upstream/downstream direction switching based on the encoded switching command detection, originating from the master modem.

There is provided a cable network device (10) comprising an output path (32), for example from a diplex filter, connected to at least one output (14) and a test port (24) associated with the at least one output (14), wherein a microstrip directional coupler (30) is disposed in the output path (32) with a coupling port (44) of the microstrip directional coupler (30) connected to the test port (24), and an amplifier element (36) and at least one equalizer (34) disposed between the coupling port (44) and the test port (24). The device is configured for signals complying with a high frequency spectrum of 1.8 GHz and above.

An automatic gain control (AGC) transimpedance amplifier (TIA) uses a differential structure with feedback PIN diodes to adjust the loop gain of the amplifier automatically to maintain stability over a wide dynamic range when converting optical power using a photodiode to an electrical signal. A stable DC current derived from the photodiode current sets the voltage gain of the amplifier. The use of ultra-linear long carrier lifetime PIN diodes assures the transimpedance feedback resistance is linear. The AGC function adjusts the gain of the TIA to provide a linear stable differential transresistance controlled by the photodiode current; a linear stable AGC function using current supplied by the photodiode; an improvement of about 10 db of the transresistance dynamic range; and reduces the need for internal and external circuitry needed to provide the same function. The TIA is applicable to CATV optical systems which have very strict linearity requirements.

The present invention is directed to a bi-directional RF signal amplifier that includes both an active communications path and a passive communications path. The circuitry is simplified and the housing size is reduced by having one port which functions as part of the active communications path when the bi-directional RF signal amplifier is powered, and that functions as part of the passive communications path when the bi-directional RF signal amplifier is unpowered.

A half duplex amplifier for a cable network.