DISTRIBUTED CONVERSION OF DIGITAL DATA TO RADIO FREQUENCY
Provided are, among other things, systems, apparatuses methods and techniques for converting digital data to radio-frequency (RF) signals. One such apparatus includes a reactive-impedance network within which the levels of multiple binary waveforms are individually boosted, before being combined to produce a single, composite output signal.
1 . An apparatus for converting digital data to radio-frequency (RF) signals, said apparatus comprising:
an input line for receiving binary-encoded data samples;
a decoder having: an input that is coupled to the input line and a plurality of outputs which provide binary waveforms based on the data samples;
a reactive-impedance network having an output and comprising a plurality of segments, with: (a) the outputs of said decoder coupled as inputs to said segments, (b) each of said segments including at least one shunt capacitive reactance and at least one series inductive reactance, and (c) said segments also including active devices;
means for compensating for unequal signal propagation delay from outputs of the shunt capacitive reactances to the output of said reactive-impedance network; and
an output line that is coupled to the output of said reactive-impedance network,
wherein said active devices of said reactive-impedance network differently boost signals derived from said decoder outputs, and
wherein signals boosted by said active devices are combined within said reactive-impedance network to produce a single, composite signal at said output of said reactive-impedance network.
2 . An apparatus according to claim 1 , wherein two or more of said decoder outputs are merged to produce at least one combined waveform which is boosted by an active device that is biased for operation as a Class A amplifier.
3 . An apparatus according to claim 1 , wherein the number of said decoder outputs is equal to the number of bits that define said binary-encoded data samples.
4 . An apparatus according to claim 1 , wherein said binary-encoded data samples are decoded into a number of binary waveforms that is equal to the number of bits that define said binary-encoded data samples.
5 . An apparatus according to claim 1 , wherein said reactive-impedance network is a singly-terminated network without any shunt resistive element.
6 . An apparatus according to claim 5 , wherein said means for compensating result in approximately equal delay from outputs of the capacitive elements of said reactive-impedance network to the output of said reactive-impedance network.
7 . An apparatus according to claim 1 , wherein said reactive-impedance network is a doubly-terminated network that is terminated at exactly one end with a shunt resistive element.
8 . An apparatus according to claim 1 , wherein said means for compensating comprises a bank of delay lines, each having an input coupled to a different one of the outputs of the decoder, and each delaying a corresponding signal by an amount that is inversely related to delay introduced to said corresponding signal by the segment through which said corresponding signal passes.
9 . An apparatus according to claim 1 , wherein at least one of said active devices within said reactive-impedance network boosts the level of a waveform that is derived from a single output of said decoder.
10 . An apparatus according to claim 9 , wherein at least one of said active devices within said reactive-impedance network is biased for operation as a Class D amplifier.
11 . An apparatus according to claim 1 , wherein said active devices within said reactive-impedance network boost levels of modulated-carrier waves.
12 . An apparatus according to claim 11 , wherein said active devices within said reactive-impedance network are biased to operate as Class AB amplifiers.
13 . An apparatus according to claim 12 , further comprising a lowpass filter that attenuates unwanted harmonics and signal images generated by said active devices.
14 . An apparatus according to claim 11 , wherein said active devices within said reactive-impedance network are biased to operate as Class D amplifiers.
15 . An apparatus according to claim 11 , wherein said modulated-carrier waves are generated by modulating replicas of a common carrier wave with separate binary waveforms using a bank of frequency-mixers.
16 . An apparatus according to claim 11 , wherein at least one of said modulated-carrier waves is generated by using a frequency-mixer to modulate a replica of a common carrier wave with a waveform that is derived by combining at least two outputs of said decoder.
17 . An apparatus according to claim 16 , wherein said modulated-carrier wave is boosted by an active device within said reactive-impedance network that is biased for operation as a Class A amplifier.
18 . An apparatus according to claim 11 , wherein plural of said modulated-carrier waves are generated by modulating a replica of a common carrier wave with separate binary waveforms, with said modulating occurring within the active devices used to boost said modulated-carrier waves.
19 . An apparatus according to claim 11 , wherein at least one of said modulated-carrier waves is generated by modulating a carrier wave with a separate binary waveform, after phase-shifting said at least one carrier wave by an amount that is inversely related to delay introduced to a corresponding signal by the segment through which said corresponding signal passes.
20 . An apparatus according to claim 11 , wherein at least two of said modulated-carrier waves are merged before being boosted as a combined waveform by said one of said active devices.
21 . An apparatus according to claim 20 , wherein said combined waveform is boosted by an active device that is biased for operation as a Class A amplifier.
22 . An apparatus according to claim 1 , wherein said reactive-impedance network includes at least one discrete capacitor.
23 . An apparatus according to claim 1 , wherein said reactive-impedance network includes a segment having plural active devices.
24 . An apparatus according to claim 1 , wherein said at least one shunt capacitive reactance in at least one of said segments comprises one of said active devices.
25 . An apparatus according to claim 1 , wherein said segments are arranged in series, so that an output of one of said segments is coupled to a second input of another of said segments.
26 . An apparatus according to claim 1 , wherein the number of active devices is not greater than the number of said decoder outputs.
27 - 37 . (canceled)
38 . An apparatus according to claim 1 , wherein said active devices provide said means for compensating by also introducing delays that compensate for unequal signal propagation through said reactive-impedance network.
39 . An apparatus according to claim 1 , wherein said at least one series inductive reactance is implemented by a device having an impedance that increases with frequency over a particular frequency range.
40 . An apparatus according to claim 1 , wherein said binary-encoded data samples and said binary waveforms reflect binary weighting.
41 . An apparatus according to claim 1 , wherein said binary-encoded data samples and said binary waveforms reflect other than binary weighting.