EP0414352A2
Expired / Lapsed
EP
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Radio transmitter with output power control
Assignee: Orbitel Mobile Communications Ltd
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Filing: 1990-06-21
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Granted: —
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Expires: 2010-06-21
Abstract
Abstract A transmitter includes a power amplifier (2), and a detector arrangement (10) coupled to the output of the power amplifier (2) for detecting the power provided by the amplifier. A voltage comparator (16) has an output connected to control the gain of the power amplifier (2), the comparator having a first input coupled to the detector arrangement (10) and a second input coupled to a digital to analogue converter (40) which is arranged to supply a control voltage to the voltage comparator (16). A control system (52), including a memory (50), is arranged to apply digital signals to the digital to analogue converter (40) representing selected power levels for the power amplifier (2). In order to prevent RF side bands caused by the edges of power pulses produced by the transmitter, the initial and final data portions clocked out of the memory (50) for a power pulse, are modified e.g. according to a cosine function.
Inventors
- 👤 Caroline Jane Watson
- 👤 Robert Owen Bristow
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 03:06
CPC Classifications
H; H04; H04W; H04W52/00; H04W52/04; H04W52/52; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3036; H03G3/3042; H03G3/3047
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
129 words
A transmitter for a radio telephone system, the transmitter including: a power amplifier (2), and means (10) coupled to the output of the power amplifier (2) for detecting the power provided by the amplifier, the transmitter being characterised in that it further includes: a voltage comparator (16) arranged to produce an output effective to control the gain of the power amplifier (2), the voltage comparator (16) having a first input coupled to the detector means (10) and a second input coupled to digital to analogue conversion means (40) for supplying a control voltage to the voltage comparator (16), and a control system (52) including a memory means (50) for applying digital signals to said digital to analogue conversion means (40) representing selected power levels for the power amplifier (2).
Claim 2
Dependent Claim
129 words
A transmitter for a radio telephone system, the transmitter including: a power amplifier (2), and means (10) coupled to the output of the power amplifier (2) for detecting the power provided by the amplifier, the transmitter being characterised in that it further includes: a voltage comparator (16) arranged to produce an output effective to control the gain of the power amplifier (2), the voltage comparator (16) having a first input coupled to the detector means (10) and a second input coupled to digital to analogue conversion means (40) for supplying a control voltage to the voltage comparator (16), and a control system (52) including a memory means (50) for applying digital signals to said digital to analogue conversion means (40) representing selected power levels for the power amplifier (2).
Claim 3
Dependent Claim
32 words
A transmitter as claimed in claim 1 wherein the output of the voltage comparator (16) provides a control signal to the base of a power transistor (30) within the power amplifier (2).
Claim 4
Dependent Claim
30 words
A transmitter as claimed in claim 1 wherein the detector means (10) comprises a directional coupler arrangement (8) coupled to rectifier means for developing a signal indicative of power sensed.
Claim 5
Dependent Claim
28 words
A transmitter as claimed in claim 1 including a phase adjustment circuit (36) coupled to the voltage comparator (16) for reducing undesirable phase shifts within the control loop.
Claim 6
Dependent Claim
37 words
A transmitter as claimed in claim 1 wherein the digital to analogue conversion means (40) is coupled to the voltage comparator (16) via a diode arrangement for compensating for temperature effects in the power detector means (10).
Claim 7
Dependent Claim
52 words
A transmitter as claimed in any preceding claim wherein the memory means (50) includes a multiplicity of memory sections, each containing data relating to a discrete power level of the power amplifier (2), and processing means (52) for clocking out data from the selected memory section for the duration of the pulse.
Claim 8
Dependent Claim
39 words
A transmitter as claimed in claim 6 wherein the initial data and final data portions clocked out of each memory section are modified in predetermined manner to reduce or eliminate RF side bands created by the power amplifier (2).
Claim 9
Dependent Claim
21 words
A transmitter as claimed in claim 7 wherein the initial and final data portions are determined according to a cosine function.
Claim 10
Dependent Claim
47 words
A transmitter as claimed in claim 6 wherein the digital to analogue conversion means (40) is coupled to the voltage comparator (16) by way of a filter (44) for reducing the slope of the trailing and leading edges of the pulse provided without introducing undesirable phase shifts.
Claim 11
Dependent Claim
42 words
A transmitter as claimed in claim 6 or 7 wherein the initial data and final data portions clocked out of each memory section are modified in a predetermined manner to take account of the non-linear characteristics of the power detector means (10).
Claim 12
Dependent Claim
117 words
A transmitter for a radio telephone system, the transmitter including a power amplifier (2), and means (10) coupled to the output of the power amplifier (2) for detecting the power provided by the amplifier (2), the transmitter being characterised in that it further includes a voltage comparator (16) having an output coupled to control the gain of the power amplifier (2) and having a first input coupled to the detector means (10) and a second input coupled to means (50,52) for providing a pulse waveform, the leading and trailing edges of the waveform having a slope such as to reduce or eliminate side bands of RF energy which would be created by edges having a steep slope.
Claim 13
Dependent Claim
117 words
A transmitter for a radio telephone system, the transmitter including a power amplifier (2), and means (10) coupled to the output of the power amplifier (2) for detecting the power provided by the amplifier (2), the transmitter being characterised in that it further includes a voltage comparator (16) having an output coupled to control the gain of the power amplifier (2) and having a first input coupled to the detector means (10) and a second input coupled to means (50,52) for providing a pulse waveform, the leading and trailing edges of the waveform having a slope such as to reduce or eliminate side bands of RF energy which would be created by edges having a steep slope.
Claim 14
Dependent Claim
43 words
A transmitter as claimed in claim 11 wherein said means for providing a pulse waveform comprises a control system including a memory means (50) containing pulse information, the memory means being coupled to the voltage comparator via digital to analogue conversion means (40).
Claim 15
Dependent Claim
39 words
A transmitter as claimed in claim 11 or claim 12 including a filter (44) coupled to the voltage comparator (16) for reducing the slope of the trailing and leading edges of the puise waveform without introducing undesirable phase shifts.
Claim 16
Dependent Claim
72 words
A transmitter as claimed in claim 12 wherein the memory means (50) includes a multiplicity of memory sections each containing data relating to a discrete power level of the power amplifier (2), processing means (52) for clocking out data from the selected memory section for the distortion of the pulse, wherein the initial and final data portions clocked out are modified in predetermined manner to reduce or eliminate RF side band surges.
Claim 17
Dependent Claim
21 words
A transmitter as claimed in claim 14 wherein the initial and final data portions are determined according to a cosine function.
Claim 18
Dependent Claim
32 words
A transmitter as claimed in claim 14 wherein the initial and final data portions are modified in predetermined manner to take account of the non linear characteristics of the power detecting means.
References Cited (Backward Citations)
No citation records indexed.
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