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The nature of the observed phenomenon of "starting resistance" is reviewed, along with the accompanying experimental evidence of high drive-level altering and sometime "curing" of the malady. A simple phenomenological model is proposed, and then it is shown that this model does indeed predict all of the observed properties of starting resistance with the exception of "high-drive curing". This same model is then shown to predict the low level intermodulation effects seen in monolithic crystal filters. The ability to predict both starting resistance and intermodulation phenomena with the same model is taken as an indication that both phenomena have a common cause. Explanations of high-drive level curing of the phenomena are contemplated.

I n t h i s p a p e r a n o s c i l l a t o r t e m p e r a t u r e Compensation technique i s outlined which can be used to compensate any resonator having a parab o l i c a l l y r e l a t e d f r e q u e n c y v e r s u s t e m p e r a t u r e c h a r a c t e r i s t i c . T h i s a p p r o a c h c o u l d b e u s e d with many of t h e low f r e q u e n c y c r y s t a l c u t s i n a d d i t i o n t o t h e BT-cut, but i s o f p a r t i c u l a r i n t e r e s t f o r u s e w i t h ST q u a r t z t y p e SAW devices. The t y p i c a l r e s o n a t o r o f t h i s t y p e h a s a t u r n i n g p o i n t i n t h e v i c i n i t y o f room temperature with a f r e q u e n c y v e r s u s t e m p e r a t u r e c h a r a c t e ri s t i c w h i c h d e c r e a s e s w i t h i n c r e a s i n g o r d ec r e a s i n g t e m p e r a t u r e . To compensate t h i s r es o n a t o r , a p a r a b o l i c c a p a c i t y f u n c t i o n i s generated which has a maximum a t t h e t u r n i n g point temperature. The c o m p e n s a t i o n c i r c u i t c o n s i s t s of two series connected varactors, with a h i g h t u n i n g r a t i o , which a r e d r i v e n by a l i n e a r v o l t a g e v e r s u s t e m p e r a t u r e f u n c t i o n . A n a l y s i s of t h i s c i r c u i t shows t h a t by a p p r o p r i a t e s e l e c t i o n o f v a r a c t o r t y p e s , a n e x a c t p a r a b o l i c c a p a c i t y f u n c t i o n c a n b e g e n e r a t e d a c r o s s a wide temperature range. Adjustment of the compensation n e t w o r k i n v o l v e s s e t t i n g t h e s l o p e and l e v e l o f t h e l i n e a r f u n c t i o n o n l y . C i r c u i t s and e x p e r im e n t a l r e s u l t s a r e shown f o r a 150 MHz SAW o s c i l l a t o r and f o r a t y p i c a l BT-cut c r y s t a l o s c i l l a t o r . I n t r o d u c t i o n A c o n s i d e r a b l e amount of work has been done in developing temperature compensation techniques f o r c r y s t a l o s c i l l a t o r s . T h i s c a n b e a t t e s t e d t o by t h e many papers which have been presented i n p a s t y e a r s a t t h i s symposium. Various approaches have been proposed including the use of t h e r m i s t o r -c a p a c i t o r n e t w o r k s i n t h e c r y s t a l o s c i l l a t i n g c i r c u i t o r p l a c i n g a v a r a c t o r i n t h e c r y s t a l l o o p a n d a p p l y i n g a c o n t r o l v o l t a g e generated by a v a r i e t y o f t e m p e r a t u r e s e n s i t i v e schemes. Most of t h i s work has involved compens a t i o n of t h e AT c u t c r y s t a l w h i c h h a s a t h i r d order type frequency versus temperature charact e r i s t i c . The p o p u l a r i t y of t h e AT c u t c r y s t a l f o r TCXO's i s understandable considering i t s s u p e r i o r a g i n g c h a r a c t e r i s t i c and t h e f a c t t h a t i t s f r e q u e n c y v e r s u s t e m p e r a t u r e i s t h e most s t a b l e o f t h e commonly u s e d c r y s t a l c u t s . Some work has been done in the past on ...

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