RF output stage amplifier

01

Size output power, gain and linearity

Mini-Circuits' ZHL-20W-13+ datasheet lists a 50 Ω, 20 W class A amplifier for 20 to 1,000 MHz (usable over 15 to 1,100 MHz) with gain of 46–55 dB (50 dB typ.), gain flatness of ±1.8 dB maximum (±1.2 dB typ.), output power at 1 dB compression of +39 dBm minimum and +41 dBm typ., saturated output at 3 dB compression of +40 dBm minimum and +43 dBm typ., 3.5 dB noise figure, +50 dBm output third-order intercept, and VSWR of 1.7:1 at input and 2.5:1 at output. [1]

Its measured table shows P1dB of 41.0–43.2 dBm and OIP3 of 47.1–53.3 dBm across 20 to 1,000 MHz, with OIP3 falling toward the top of the band. [1]

Editorial calculation: +41 dBm is about 12.6 W. With 50 dB gain the amplifier reaches it from about −9 dBm input, which sits 6 dB below the −3 dBm no-damage input limit. At 24 V and 2.8 A the DC input is 67 W, so efficiency at P1dB is about 19% and about 55 W must leave through the heat sink. [1]

Editorial note: specify the power you need at 1 dB compression at the highest frequency, since saturated power and mid-band figures overstate what a linear stage delivers at the band edge. [1]

Give the supplier the frequency range, output power required at P1dB (and Psat if pulsed or CW saturated use), gain and flatness, linearity (OIP3, ACPR or harmonics), noise figure if relevant, input and output VSWR, load mismatch it must survive, DC supply, duty cycle, cooling (heat sink, fan, liquid), protection features, connectors, size and quantity.

02

Plan input drive, load protection and heat removal

The ZHL-20W-13+ datasheet lists absolute maximum ratings of 28 V DC, −3 dBm RF input (peak envelope power) into a 50 Ω load, base-plate temperature of 85 °C and operation from −20 to +65 °C. It says the amplifier withstands a full mismatch (short or open) at any phase if input power does not exceed −13 dBm, that open load is not recommended, and that with no load the maximum input must be derated by 20 dB. It shuts off automatically on overheating. [1]

For the version without heat sink and fan, the datasheet says the user must remove heat to keep the base plate at or below 85 °C, which requires an external heat sink of 0.38 °C/W or lower thermal resistance; the unit weighs 750 g with heat sink and 290 g without. [1]

Linked suppliers list broadband high-power amplifiers from 0.5 to 2.7 GHz at 20 to 100 W with 44–50 dB gain, and state ranges “from 1MHz to 18GHz with a variety of power ratings from several watts to kilo-watts” [2], and solid-state power amplifier modules from 20–1,000 MHz at 100 W to 6–18 GHz at 300 W. [3]

03

Compare what suppliers offer

Suppliers linked to this page list RF power amplifiers; each card links to the page reviewed.

The listings reviewed cover broadband multi-octave amplifiers and GaN solid-state modules up to 300 W. Ask each for measured P1dB, gain and VSWR against frequency, efficiency, load-mismatch survival and thermal requirements. [2] [3]

04

Compare a rack amplifier's P1dB, load tolerance and mains draw

Rohde & Schwarz's November 2025 specifications for the R&S BBA130 broadband amplifier list the BBA130-BC100 for 80 MHz to 1 GHz instantaneously into 50 Ω, with a minimum of 100 W (50.0 dBm) in high power mode and a minimum of 70 W (48.5 dBm) at 1 dB compression, nominal gain of 51.9 dB at 400 MHz, gain flatness under ±3 dB, harmonics at 70 W in class A below −20 dBc and noise figure below 10 dB. [4]

The datasheet lets the user trade output against load tolerance: power mode adjusts continuously between Psat at a VSWR of 2:1 (high power mode) and P1dB at a VSWR of 6:1 (VSWR mode), and bias adjusts continuously between class A and class AB. Input level for 70 W is −3.4 dBm nominal, maximum input is +15 dBm, and input VSWR is 2:1 maximum. The unit is a 4 HU 19-inch chassis of 430 × 196 × 580 mm weighing about 16 kg, running from 100 to 240 V AC with a rated current of 8.6 A at 110 V or 4.1 A at 230 V and rated power of 930 VA at 100 W CW. [4]

Editorial calculation: −3.4 dBm plus 51.9 dB gain gives 48.5 dBm, the 70 W P1dB figure; 100 W RF out against 930 VA in is about 11%, so plan cooling and mains capacity for close to the full 930 VA. P1dB sits 1.5 dB below Psat (48.5 against 50.0 dBm). [4]

05

Trace what each part controls

This is a functional reference built from the sources cited; it is not one maker's specification.

06

Fill the specification fields with values for your system

An RF amplifier quotation needs values for your system. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the band, power and thermal data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Band: [MHz–GHz]
Power: [P1dB; Psat; CW or pulsed]
Gain: [dB; flatness]
Linearity: [OIP3; harmonics]
Match: [VSWR; mismatch survival]
Supply: [V; A]
Cooling: [heat sink; fan; ambient]
Connectors/size: [type; outline]
Quantity: [units]

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