Application Notes
For further information about our Ultra Wide Band Voltage Controlled Oscillators, VCOs, we refer to the text below. The information is also available in a pdf.
Application Notes VO3280 VCO Series (1.4 MB PDF-file)
General Description
The VO3280 VCO is a drop-in Voltage Controlled Oscillator intended for any application where size and performance is important.
Wideband and Low Noise are optimized, still appreciating low current consumption and high output power. The VO3280 VCO series is also available in various packages with SMA connectors and solder pins.
To make the assembly easier, the VCO can be equipped with wires and ribbons in the factory. Consult Sivers IMA for details. Application notes described in this document are applicable on all VCO’s in this series.
The VCO’s are manufactured in a class 10.000 clean room.
Features • High Bandwidth
• Low Noise
• High Linearity
• Medium High Power
• Extended temperature range
• Hermetically sealed
• Drop-in or in housing (VO4280)
• Standard housings available
• Custom housings available
• Custom frequency ranges
• Coplanar RF port available (VO3284)
Standard Models
• VO3280S/01 2-3GHz 15dBm
• VO3280S/00 3-5GHz 15dBm
• VO3280C/00 5-8,4GHz 15dBm
• VO3280X/00 8,4-13,5GHz 15dBm
• VO3280P/00 13,5-20GHz 15dBm
Block Diagram VCO Turning interface
Connections
All connections should be wire or ribbon bonded. Use of wedgebonder or parallel gap welder is recommended. Temperature during assembly should not exceed 200°C.
Conductive adhesive could be used as an option. Do not attempt to solder any connections. The shape and quality of the RF output bond, both stripline and ground, is crucial. See details below for your application
Wire recommendations
RF output 2x25μm gold wire or 1x250μm gold ribbon
Tune input 75μm gold wire
Bias input 75μm gold wire
Ground through carrier
Material
The Carrier and Lid is made of Kovar, Gold plated over a barrier of Nickel. The substrate is ceramic and the connections are Gold plated on Tantalum Nitride.
Assembly example with 75μm wires on Bias(U) and Tune(T). RF output is bonded with two 25μm wires.
Ground(G) wire is optional as the VCO is grounded through the carrier.
Electrical Requirements and Features
Bias
Even though the VCO is fitted with an internal regulator, a low noise power supply and proper bias filtering is important to obtain a low noise RF signal. Avoid using a switched (switch-mode) power supply directly on the bias input, or be extra careful with the bias filtering. A linear power supply is recommended. A 100nF capacitor close to the bias connection is preferred.
Tune
The oscillators Tuning Input Voltage is somewhere between 0V and +20V. See the individual Test Reports for exact Tuning v.s. Frequency characteristics. Normally the tuning current is below 100μA. There is some RF-leakage on the Tune and Bias terminals.
On demand, the tuning bandwidth can be adjusted to >100MHz.
S- and C-band oscillators are normally temperature compensated bipolar oscillators that will not oscillate below 2V tuning voltage.
If the oscillator should be running at all times, i.e. idle in a PLL, the tuning voltage should be kept above 2V in order to keep the PLL locked.
RF output
The RF output is a 250μm wide stripline, Zo=50Ω. The RF out is AC-coupled with a 10pF cap.
A built in lowpass filter reduces the harmonic to better than -25dBc.
Since this is a fundamental oscillator, there are no sub harmonics.
Higher harmonics are generally lower than the second harmonics.
The VO3280 series provides up to +18dBm output power. A coplanar GSG output (Ground-Signal-Ground) is available.
Documentation
All SiversIMAs products are delivered with full Test Report in digital form. The Test Report contains all measured data and graphs, showing the VCO’s Tuning and Power characteristics, as well as Noise Performance.
The products are also delivered with Certificate of Conformity (CoC) and Certificate of Origin (CoO) upon request.
| Standard Frequency Band |
Drop-in Stripline | Drop-in Coplanar |
SMA-SMA Housing |
SMA - Solder Pin Housing |
| 2-3 GHz | VO3280S/01 | VO3284S/01 | VO4280S/01 | VO4283S/01 |
| 3-5 GHz | VO3280S/00 | VO3284S/00 | VO4280S/00 | VO4283S/00 |
| 5-8,4 GHz | VO3280C/00 | VO3284C/00 | VO4280C/00 | VO4283C/00 |
| 8,4-13,5 GHz | VO3280X/00 | VO3284X/00 | VO4280X/00 | VO4283X/00 |
| 13,5-20 GHz | VO3280P/00 | VO3284P/00 | VO4280P/00 | VO4283P/00 |
Application Recommendations
General
Avoid use of thermal compound. Use a minimum of screw-lock adhesive in order to prevent it from entering between the carrier and heat sink.
The heat sink should be able to dissipate 4 Watts, keeping the base temperature below 65°C, unless the VCO is ordered with an extended temperature range. Operating temperatures up to +85°C and -45°C is available.
Application where the VCO is connected to a coaxial connector
Mechanical design
The radius between the bottom and wall should be kept below 100μm. See Figure 1 and mechanical drawing AN3280_1.
Preparations
SMA contacts should be assembled and the VCO prepared with wires or ribbon before it is mounted in place. This will make the connections easier. The ribbon and wires could be pre-mounted in factory. Contact Sivers IMA.
The RF output connection is most important. Extra effort should be used above 12GHz. Make sure that the signal ground path is as short as possible. The VCO’s carrier and the receiving units ground plane should be in good physical contact. The gap should not exceed 100μm. If conductive epoxy is used to ensure contact, be careful not to contaminate the substrate around the RF stripline. If there is necessary to remove any residue on the substrate, avoid using metal tools, as this will contaminate the substrate with metal instead.
Connecting the VCO to a aluminium oxide substrate
Mechanical design
The VCO’s substrate and the receiving substrate should be in the same level to keep the RF output bonds short.
It is important to keep the distance between the signal grounds short. See Figures 3a, 3b and mechanical drawing AN3280_2 for details.
Two examples of assembly
Connecting to a mixed PCB i.e. FR4 and Rogers. This is probably the most common application. A VCO is connected to a high frequency PCB, such as Rogers 3003, providing high frequency capabilities.
The main concern is the distance between the VCO and the receiving PCB. Make sure that the VCO and PCB is assembled as close to each other as possible. See Figure 4. The FR4 should have ground plane vias close to the VCO, providing good signal ground to the Rogers substrate.
The Drop-in coplanar type VCO (VO3284 series) is ideal for this type of application.
Application examples
DTO (Digitally Tuned Oscillator) example.
The table of calibrated frequency values is stored in the EEPROM. Temperature drift is eliminated thanks to the fact that the VCO is temperature stabilized either with an oven set for e.g. 55°C, or a Peltier thermoelectric module set for e.g. 35°C.
Synthesizer example. Provides high accuracy and eliminates the need for calibration. The Synthesizer has no temperature drift.
Example of double Coherent Radar Jammer with Noise Generator, where both LO’s and Noise sources are VO3280 series VCO’s.