Stanford Research-RF Signal Generators (Model:SG380 Series)

 The SG380 Series RF Signal Generators use a unique, innovative architecture (Rational Approximation Frequency Synthesis) to deliver ultra-high frequency resolution (1 µHz), excellent phase noise, and versatile modulation capabilities (AM, FM, ØM, pulse modulation and sweeps) at a fraction of the cost of competing designs.

The standard models produce sine waves from DC to 2.025 GHz (SG382), 4.05 GHz (SG384) and 6.075 GHz (SG386).

SG380 Series RF Signal Generators

Introducing the new SG380 Series RF Signal Generators — finally, high performance, affordable RF sources.

The SG380 Series RF Signal Generators use a unique, innovative architecture (Rational Approximation Frequency Synthesis) to deliver ultra-high frequency resolution (1 µHz), excellent phase noise, and versatile modulation capabilities (AM, FM, ØM, pulse modulation and sweeps) at a fraction of the cost of competing designs.

The standard models produce sine waves from DC to 2.025 GHz (SG382), 4.05 GHz (SG384) and 6.075 GHz (SG386). There is an optional frequency doubler (Opt. 02) that extends the frequency range of the SG384 and SG386 to 8.10 GHz. Low-jitter differential clock outputs (Opt. 01) are available, and an external I/Q modulation input (Opt. 03) is also offered. For demanding applications, the SG380 Series can be ordered with a rubidium timebase (Opt. 04).

On the Front Panel

Phase Noise

Amplitude Modulation

The SG380 Series Signal Generators have two front-panel outputs with overlapping frequency ranges. A BNC provides outputs from DC to 62.5 MHz with adjustable offsets and amplitudes from 1 mV to 1 Vrms into a 50 Ω load. An N-type output sources frequencies from 950 kHz to 4.05 GHz with power from +16.5 dBm to -110 dBm (amplitude from 1 Vrms to 0.707 µVrms) into a 50 Ω load.

Modulation

The SG380 Signal Generators offer a wide variety of modulation capabilities. Modes include amplitude modulation (AM), frequency modulation (FM), phase modulation (ΦM), and pulse modulation. There is an internal modulation source as well as an external modulation input. The internal modulation source produces sine, ramp, saw, square, and noise waveforms. An external modulation signal may be applied to the rear-panel modulation input. The internal modulation generator is available as an output on the rear panel.

Unlike traditional analog signal generators, the SG380 Series can sweep continuously from DC to 62.5 MHz. And for frequencies above 62.5 MHz, each sweep range covers more than an octave.

Frequency Modulation

1 GHz Spectra

OCXO or Rubidium Timebase

The SG380 Series come with a oven-controlled crystal oscillator (OCXO) timebase. The timebase uses a third-overtone stress-compensated 10 MHz resonator in a thermostatically controlled oven. The timebase provides very low phase noise and very low aging. An optional rubidium oscillator (Opt. 04) may be ordered to substantially reduce frequency aging and improve temperature stability.

The internal 10 MHz timebase (either the standard OCXO or the optional rubidium reference) is available on a rear-panel output. An external 10 MHz timebase reference may be supplied to the rear-panel timebase input.

Square Wave Clock Outputs

Optional differential clock outputs (Opt. 01) are available on the rear-panel that make the SG384 a precision clock generator in addition to a signal generator. Transition times are typically 35 ps, and both the offset and amplitudes of the clock outputs can be adjusted for compliance with PECL, ECL, RSECL, LVDS, CML, and NIM levels.

Frequency Shift Keying (FSK)

Pulse Modulation

I/Q Inputs

Optional I/Q inputs (Opt. 03) allow I & Q baseband signals to modulate carriers from 400 MHz to 4.05 GHz. This option also allows the I/Q modulator to be driven by an internal noise generator with adjustable amplitude and bandwidth. Rear-panel outputs allow the noise source to viewed or used for other purposes.

Output Frequency Doubler

The SG384 and SG386 can be ordered with a frequency doubler (Opt. 02) that extends the frequency range to 8.10 GHz. The amplitude of the rear-panel RF output can be adjusted from –10 dBm to +13 dBm. This option also comes with a bias source output which can be set with 5 mV resolution over ±10 VDC.

Easy Communication

Remote operation is supported with GPIB, RS-232 and Ethernet interfaces. All instrument functions can be controlled and read over any of the interfaces. Up to nine instrument configurations can be saved in non-volatile memory.

A New Frequency Synthesis Technique

The SG380 Series Signal Generators are based on a new frequency synthesis technique called Rational Approximation Frequency Synthesis (RAFS). RAFS uses small integer divisors in a conventional phase-locked loop (PLL) to synthesize a frequency that would be close to the desired frequency (typically within ±100 ppm) using the nominal PLL reference frequency. The PLL reference frequency, which is sourced by a voltage control crystal oscillator that is phase locked to a dithered direct digital synthesizer, is adjusted so that the PLL generates the exact frequency. Doing so provides a high phase comparison frequency (typically 25 MHz) yielding low phase noise while moving the PLL reference spurs far from the carrier where they can be easily removed. The end result is an agile RF source with low phase noise, essentially infinite frequency resolution, without the spurs of fractional-N synthesis or the cost of a YIG oscillator.

Noise Spectra

I/Q Noise Modulation

Polar Plot 1

Clock Outputs

Polar Plot 2