MLTOSeries permanentmagnet YIG oscillators

MLTO-Series permanent-magnet YIG oscillators can be supplied in 0.875-in.-diameter TO-8 housings with pin or coaxial connectors and operating frequencies to 13 GHz.

TO-8 YIGs Tune 3 To 13 GHz

These compact microwave oscillators can tune across customer-specified bands with generous output power, featuring low levels of spurious and SSB phase noise.

Oscillators can be built from many different types of resonators. Perhaps one of the most reliable for high-frequency applications is the yttrium-iron-garnet (YIG) sphere, the heart of YIG-tuned oscillators. At one time, such tunable sources were relatively large and heavy. But with new models such as the second-generation MLTO-Series of permanent-magnet YIG oscillators from Micro Lambda Wireless (www.microlambdawireless.com), these microwave oscillators take up no more space than a small coin on a printed-circuit board (PCB). Diminutive oscillators in the MLTO Series are supplied in tiny TO-8 housings and are available in selected tuning ranges from 3 to 13 GHz.

The MLTO-Series TO-8 permanent-magnet YIG oscillators can be constructed with pin or coaxial connectors (see figure). They are designed for operating voltages of +8 and -5 VDC and deliver consistent performance across operating (case) temperatures from 0 to +65°C. The oscillator series currently includes models MLTO-50365 for use from 3.0 to 6.5 GHz, MLTO-50409 for use from 4.0 to 9.0 GHz, and MLTO-50613 with a tuning range of 6.5 to 13.0 GHz. Each oscillator has a free-running frequency, such as 4.7 GHz in the MLTO-50365, which is varied as current is applied to the permanent-magnet resonant cavity with its YIG sphere.

Each of the models provides at least +10 dBm output power across its tuning range, with worst-case power variations contained within a 3-dB window. Frequency drift over temperature is a maximum of ±25 MHz in the two lower-frequency oscillators and only ±20 MHz in the MLTO-50613. This performance across temperature comes without need for an additional heater.

As an example of the large performance available from these small oscillators, model MLTO-50365 exhibits harmonics of -12 dBc or better and spurious levels of -70 dBc or better from 3.0 to 6.5 GHz. It has phase noise of -100 dBc/Hz or better offset 10 kHz from the carrier, improving to -128 dBc/Hz or better offset 100 kHz from the carrier, and typically -130 dBc/Hz offset 100 kHz from the carrier. It suffers typical pulling of frequency of a mere 2 MHz into a load with 12-dB return loss, and typical pushing with power supply of 2 MHz/V at +8 VDC.

As with the other oscillators in the series, the MLTO-50365 has a main tuning coil and a frequency-modulation (FM) coil for modulation and phase-locking purposes when used in a frequency synthesizer design. The main coil sensitivity is typically 9 MHz/mA while the FM coil sensitivity is 150 kHz/mA. The MLTO-50365 YIG oscillator draws a maximum of 60 mA from +8 VDC and 20 mA from -5 VDC.

Moving up in frequency, model MLTO-50409 tunes from 4.0 to 9.0 GHz, with harmonic and spurious levels that meet or exceed -12 and -70 dBc, respectively. The phase noise is -100 dBc/Hz or better offset 10 kHz from the carrier and -128 dBc/Hz or better offset 100 kHz from the carrier, with typical phase noise of -130 dBc/Hz offset 100 kHz from the carrier. Frequency pulling is typically 2 MHz into a 12-dB-return-loss load while frequency pushing is typically 2 MHz/V with supply variations centered at +8 VDC. The main tuning coil sensitivity is typically 15 MHz/mA while the FM tuning coil sensitivity is typically 150 kHz/mA. Model MLTO-50409 draws maximum power of 60 mA from a +8-VDC supply and 20 mA from a -5-VDC supply.

The highest-frequency model currently in the series, the MLTO-5613, operates from 6.5 to 13.0 GHz, with similar tuning characteristics as the other two units. It also exhibits harmonics of -12 dBc or better and spurious performance of -70 dBc or better. The phase noise is at least -98 dBc/Hz offset 10 kHz from the carrier and at least -123 dBc/Hz offset 100 kHz from the carrier, with typical phase noise of -125 dBc/Hz offset 100 kHz from the carrier. The MLTO-5613 operates on 60 mA at +8 VDC and 15 mA at -5 VDC.

This second generation of these tiny TO-8 YIG oscillators benefits from lessons learned in permanent-magnet construction and TO-8 packaging and enhanced performance from low-noise silicon-germanium (SiGe) transistors as the active devices. The TO-8 packages are only 0.5 in. tall with 0.675-in. diameter, facilitating attachment to tight spots on PCBs. Extended temperature models to +85°C are available for all models. P&A: 6 wks. ARO. Micro Lambda Wireless, Inc., 46515 Landing Pkwy., Fremont, CA 94538; (510) 770-9221, FAX: (510) 770-9213; www.microlambdawireless.com.

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