Murata Manufacturing Co., Ltd. has commercialized a small, light-weight SAW duplexer (*1) for CDMA800 (*2) terminals: SAYZW836MAF0F00.
By switching the mounting method of the piezoelectric element from the previous wire bond construction to a flip-chip construction, the product's footprint is reduced to 3.0x2.5x0.80 (max.) mm, which is 52% smaller than our previous product.
Although this product is smaller, lower loss and higher isolation characteristics are obtained through optimization of the piezoelectric element material and electrode design.
In terms of reliability, it is a highly airtight structure with excellent thermal shock characteristics (HST: 1000 cycs) (*3). Also, by incorporating Murata's own high power durability film formation process, a warranted product life of 50,000 hours under ambient temperature of 50°C at 1.0W is achievable.
This product has been mass-produced at two million units per month since May 2005. Five million units per month are scheduled to be produced starting in October 2005.
Designs with smaller RF circuitry are becoming more of a trend each year and this has resulted in the need for smaller and lower profile duplexers along with higher isolation characteristics. The outcome of this will mean that product development must focus on downsizing and improving performance simultaneously.
Normally, isolation tends to deteriorate in a small package due to coupling between the internal elements. We have therefore incorporated a new simulation approach from the package design stage to re-evaluate an optimal structure in order to achieve high isolation.
In terms of reliability, securing enough strength in the flip-chip construction and power durability characteristics compared to the previous model are strongly required. The strength in the flip-chip construction was realized with technology developed through SAW filters. Power durability characteristics, generally considered difficult to co-exist simultaneously with downsizing piezoelectric elements, were secured sufficiently through re-evaluation of the construction method and materials.
A duplexer is a component which unifies branching circuitry and Tx/Rx filters in one package in order to share one antenna with the wireless communication equipment's Tx and Rx components.
CDMA800 is an 800MHz band digital mobile communication system used in countries including North America, China and Korea. It's assigned frequencies are 824 to 849MHz for the terminal transmitting band and 869 to 894MHz for the terminal receiving band.
HST (Heat Shock Test)
HST is one of the reliability assessment methods used. Murata Manufacturing conducts HST with [normal temperature] -> [-40°C 30min.] -> [normal temperature] -> [+85°C 30min.] as one cycle.
- Small and low profile
- Low insertion loss, high attenuation and high isolation
- High power durability
- Can be mounted with lead free soldering, characterized by Sn-Ag-Cu. Reflow soldering at the peak temperature of 260°C is possible.
Duplexer for CDMA800
Following electric characteristics are realized.
At a temperature between -30°C and +85°C<
|Tx filter characteristics
|Rx band attenuation
|Rx filter characteristics
|Tx band attenuation
||Tx band attenuation
|Rx band attenuation
Tx end -> Antenna end
Antenna end -> Rx end
Tx end -> Rx end (isolation)
Starting Month for Sales
2 million units per month as of June 2005
5 million units per month scheduled starting in October 2005