Broadband diplexed or multiplexed power amplifier
A wideband amplifier includes a first diplexer receiving broadband input signals and divides them by frequency into a low band input signal and a high band input signal. The amplifier has separate high band and low band amplifiers coupled to amplify the low and high band input signals, and a second diplexer coupled to combine outputs of the low and high band amplifiers to form a wideband output. A method of amplification of an input signal includes separating the input signal into high and low band signals, separately amplifying the high and low band signals, and combining amplified high and low band signals into an output signal.
1. A wideband amplifier configured to receive a broadband input signal and provide an amplified broadband output signal comprising:
a first multiplexer coupled to receive the broadband input signal and to divide the broadband input signal by frequency into a first-band input-signal and a second-band input-signal, the first-band input-signal having a lower frequency band than the second-band input-signal;
a first band amplifier coupled to amplify the first-band input-signal and provide a first band output signal;
a second band amplifier coupled to amplify the second-band input-signal and provide a second band output signal; and
a second multiplexer coupled to combine the first band output signal and the second band output signal into the amplified broadband output signal;
wherein: (i) a frequency range of the first-band input-signal overlaps a frequency range of the second-band input-signal in a transition region; and (ii) a frequency range of the first band amplifier overlaps a frequency range of the second band amplifier in the transition region;
wherein, for frequencies in the transition region, a first signal path through the first multiplexer, the first band amplifier, and the second multiplexer has a first group delay matching a second group delay of a second signal path through the first multiplexer, the second band amplifier, and the second multiplexer; and
the second multiplexer is configured to sum the first band output signal with the second band output signal to provide gain in the transition region.
2. The wideband amplifier of claim 1 wherein each of the first band amplifier and the second band amplifier is selected from a group consisting of class A amplifiers, class AB amplifiers, class B amplifiers, Class D amplifiers, Class E amplifiers, Class F amplifiers, Class H amplifiers, Class J amplifiers, Class AB push-pull, Class B push-pull, Doherty amplifiers, supply modulated amplifiers, and class C amplifiers.
3. The wideband amplifier of claim 1 wherein the first multiplexer and the second multiplexer are passive.
4. The wideband amplifier of claim 1 wherein each of the first multiplexer-and the second multiplexer is a diplexer.
5. The wideband amplifier of claim 1 wherein input impedances and output impedances of each of the first multiplexer and the second multiplexer are about 50 ohms, across all frequency bands of interest.
6. The wideband amplifier of claim 1 where the first multiplexer has an input impedance of about 50 ohms and an output impedance other than 50 ohms across all frequency bands of interest.
7. The wideband amplifier of claim 6 where the first band and second band amplifiers have an input impedance other than 50 ohms.
8. The wideband amplifier of claim 1 wherein the second multiplexer includes one of a bandpass filter and a lowpass filter that rejects harmonics generated in the first band and second band amplifiers.
9. The wideband amplifier of claim 1 wherein the second multiplexer is configured to prevent formation of intermodulation products from a first signal in the first-band input-signal mixing with a second signal in the second-band input-signal.
10. The wideband amplifier of claim 1 , the first multiplexer being configured to further divide the broadband input signal by frequency into an additional band input signal; and further comprising:
an additional band amplifier coupled to amplify the additional band input signal to provide at an additional band output signal;
the second multiplexer further combining the additional band output signal with the first and second band output signals into the amplified broadband output signal; and
wherein a frequency range of the additional band input signal overlaps with one of (i) the frequency range of the first-band input-signal and (ii) the frequency range of the second band input signal.
11. The wideband amplifier of claim 1 , wherein each band amplifier has a narrower sub-band frequency of operation than the wideband amplifier.
12. The wideband amplifier of claim 1 , wherein the first multiplexer multiplexes the broadband signal independently with minimized insertion loss in the first band and second band frequency ranges, and minimized combining loss in the transition region frequency range, having high first band rejection in the second band and high second band rejection in the first band frequency ranges.
13. The wideband amplifier of claim 12 wherein each multiplexer comprises at least a low-pass filter and a high-pass filter.
14. The wideband amplifier of claim 12 where each multiplexer comprises-at least a first-band bandpass filter and a second-band bandpass filter.
15. The wideband amplifier of claim 14 , wherein the high-frequency three-decibel cutoff frequency of the first-band bandpass filter of the first multiplexer is equal to the low-frequency three decibel cutoff frequency of the second-band bandpass filter of the first multiplexer.
16. The wideband amplifier of claim 15 wherein the first-band bandpass filter of the first multiplexer comprises a shorted segment of transmission line and an open segment of transmission line.
17. The wideband amplifier of claim 15 wherein the first-band bandpass filter of the first multiplexer comprises a Butterworth filter.
18. The wideband amplifier of claim 1 , wherein each band amplifier has an output impedance adjusted for a flat output power response over an entire wideband frequency range of the wideband amplifier.
19. The wideband amplifier of claim 1 where the first band and second band amplifiers have an output impedance other than 50 ohms.
20. The wideband amplifier of claim 1 where the second multiplexer has an output impedance of close to 50 ohms and an input impedance other than 50 ohms across all frequency bands of interest.
21. The wideband amplifier of claim 1 , further comprising a delay-compensating filter in one of the first signal path and the second signal path.
22. The wideband amplifier of claim 1 , further comprising, in one of the first signal path and the second signal path, a transmission line that equalizes group delay in the first signal path and the second signal path.